1. Field of the Invention
The present invention relates to an agricultural composition comprising an effective amount of a sulphur active ingredient and at least one dispersing agent.
2. Description of the Related Art
All the crops need balanced fertilization and presently high emphasis is laid on N—P—K as major nutrients for fertilizer applications. However, in the past couple of years sulphur has gained importance as a fourth major nutrient and its requirement in various crops and soils is increasing world wide due to the decrease in sulphur emissions and hence lower depositions into the soil.
Sulphur is known as an elemental fertilizer for feeding plants and is an essential component of certain vitamins and enzymes of plants. Sulphur, together with phosphorus and nitrogen takes part in the synthesis of certain plant proteins. Sulphur is insoluble in water, is easily inflammable and also displays irritable action on the human body. These properties of sulphur influence both its production as well as its use in the agricultural field.
Sulphur is also used as a rectifier of certain structural characteristics of the soil, including in particular its pH, which it shifts towards acidic values for alkaline soils. Sulphur is naturally present in the soil as a component of certain salts. When sulphur is oxidized to its sulphate form it serves as an essential nutrient for plant growth as sulphate is the only form in which plants can take up sulphur. Presently, sulphur is typically blended with other granular fertilizers such as phosphates, nitrates, urea and potash among others to provide it in a form suitable for application to the soil. Sulphur is available commercially as prills, soluble sulphur liquids, wettable powders and micronized powders. These compositions are then applied to the soil by various means such as broadcasting or banding to supply the soil with sulfur, as well as additional nutrients found in the granular fertilizers.
One problem associated with the use of these conventional compositions is that they need to be applied in very high dosages. The applicable dosage of these conventional compositions per acre is very high and can extend from about 10 kg/acre for Sulphur bentonite compositions to about 25 kg per acre for Sulphate based fertilizers and goes all the way to more than 100 kg/acre in case of gypsum. Also since these conventional compositions are used in high dosages there is an increased possibility of leaching in the soil making it unavailable to the plant for uptake. Large amount of money is being spent for drip and sprinkler irrigation for several horticultural crops and the use and practice of drip irrigation is increasing considerably. However, the conventional fertilizers comprising sulphur or sulphur plus bentonite mixtures cannot be applied through drip irrigation as the particle size of these compositions are large and the particles do not disperse in water, causing nozzle clogging in the irrigation equipment and resulting in a non-homogenous tank mixture at the time of application. These conventional compositions such as pellets and wettable powders do not exhibit uniform suspension resulting in uneven coverage on the plant and thereby affecting and minimizing the bio-efficacy of the product. They also need to be applied two to three months in advance so as to ensure timely conversion to sulphate and its uptake by the plant for which there is additional application and cost. Conventionally, acids such as sulfuric acid, nitric acid and/or phosphoric acid and ammonia (anhydrous) are used to produce these conventional fertilizers. The use of these chemicals creates a potentially hazardous environment for production of the fertilizer. In developing countries, these chemicals may be less available with the consequence that fertilizer must be imported at a considerable expense and crop yields are reduced in areas where food is most needed.
Sulphur has also been incorporated in fertilizer compositions for a different purpose. Specifically, sulphur has been used in the manufacture of compositions such as Sulphur bentonite pellets, Calcium Sulphate, Ammonium Sulphate and other sulphate based compostitions of fertilizers, the process of conversion of Sulphur to sulphate form is slow and sulphate is the only form in which plants can take up sulphur. In the conventional sulphur based fertilizers it is observed that sulphur is not timely converted into sulphate and hence is not readily available to the plant.
There is a need, therefore, to develop a composition which converts sulphur to its sulphate form almost instantly to be available for uptake by the plants and which delivers sulphur and other nutrients uniformly and effectively to the soil and the plant does not need to be applied in advance or as an additional application and can be applied with ongoing applications. Also there is a need to reduce the dosage substantially so as to develop a composition which is economical to the farmers. The composition exhibits a good suspension and dispersion properties in water and soil moisture so as to be miscible with other soluble fertilizers and hence applicable through drip and sprinkler irrigation to ensure a uniform spray and availability.